[gtk: 2/3] stack: Fix check if page is selected

[Matthias Clasen <matthiasc src gnome org>]

commit e211740da6ced87ec59a7231be2e3fba64d2dfb2
Author: Mohammed Sadiq <sadiq sadiqpk org>
Date:   Wed Mar 24 20:23:09 2021 +0530

    stack: Fix check if page is selected
    
    When there is no visible child, gtk_selection_model_is_selected()
    was returning TRUE for any invalid position.
    
    So check if the page is non-NULL and match

 gtk/gtkstack.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtkstack.c b/gtk/gtkstack.c
index 9b1488b3b2..e784b0c30f 100644
--- a/gtk/gtkstack.c
+++ b/gtk/gtkstack.c
@@ -562,7 +562,7 @@ gtk_stack_pages_is_selected (GtkSelectionModel *model,
 
   page = g_list_nth_data (priv->children, position);
 
-  return page == priv->visible_child;
+  return page && page == priv->visible_child;
 }
 
 static void set_visible_child (GtkStack               *stack,